When Europeans first went sailing around the globe, and bumped into (or more accurately, collided with) other more primitive societies, they asked themselves the question "How is it that we have the ships, guns, horses, writing and all the other trappings of civilization that allow us to conquer those others who have little of none of these advantages?". In the absence of any scientific explanation of how Man came to spread himself over the earth, Europe explained its success in terms of racial superiority, or believing in the 'right' God, or both. Five hundred years later, the same science that developed the ships and guns finally delivered the answer to that question.
It has been the consensus for some time now, and expressed in an accessible way by writers like Stephen Jay Gould and Luigi Luca Cavalli-Sforza, that all currently living members of the genus Homo are, genetically speaking, brothers. We are Homo Sapiens sapiens, distinguished from our ancestors (say some) by our faculty for language, and we probably first appeared in Africa about 100,000 years ago. If you read Jared Diamond's Guns, Germs and Steel you'll find a patiently paced description of the "broad sweep of history": the initial many colonizations of the globe by Homo Sapiens sapiens, and the more recent one that led to the Eurasian conquest of the rest of the planet (the result of which is clearly visible both here in New Zealand and back in Australia).
If you don't read Diamond's book, let me try to lay out its thesis in a nutshell. It was Europeans' guns, ships, germs, horses and political/societal size and sophistication that led to its victory over North- and South-Americans, SE Asians, Polynesians, Africans and Australian Aboriginals. These are the self-evident proximate causes of conquest. The ultimate causes lie in Eurasia's early transition from a hunter-gatherer lifestyle to farming. The production of excess food created a positive feedback loop with increased population densities - the more food, the more people, the more labour, the more food. This led to a necessary stratification in society: chiefdoms and kingdoms - a means by which strangers living in close proximity could co-exist more or less in peace, with the kingdom acting as arbiter, and central point of trade. (Smaller societies, based around the tribe structure, kept the peace and managed trade through personal ties and reputation: Everyone knew everyone else, perhaps even related.) Stratification led to a specialised craftsman class, freed from the direct production of food, able to invest energy inventing better tools, methods, metallurgy and so on. This was the initial vector whose trajectory finally brought literacy, science and technology.
The domestication of animals, and their subsequent living in close quarters with man (very close, according to what Australians say about New Zealanders ;-) ) led to the co-evolution of epidemic diseases, and partial human immunity in farming populations. Most of the fatalities in subsequent collisions between Old and New Worlds were due to disease rather than warfare.
So that's a very basic description of the connection between the switch to farming and its consequences in terms of the proximate causes of Eurasian conquest.
So the question now can be reduced to: how and why did Eurasians switch to farming earlier than their global cousins? Those disposed to race-based answered will have the opportunity here to insist that Eurasians were simply smarter than their cousins. This is an easy solution but there is no reputable evidence for this. Diamond's gives an extremely comprehensive answer that can be reduced to one word: luck. Culo. Bald, unearned fortune. The more extended answer, in three words, is location, location, location. The fertile crescent and the Yangtze and Yellow rivers where agriculture first began, were home to the great bulk of those wild cereals, roots fruit and animals that firstly lent themselves to domestication and secondly provided enough calories in a single 'package' to compete with and displace hunter-gatherer modes of existence. While Man experimented globally with farming, Eurasia was by a wide margin the best-equipped laboratory (and also has a geographical axis that was best disposed to a transmission of newly domesticated crops, animals and techniques).
Maori vs Australian Aboriginal
Some peoples suffered more than others during the Eurasian conquest. Few fell apart quite as much as the Australian Aboriginal. In a later post, I'll finally try to make a comparison between what happened here in New Zealand to the Maori, and what happened in Australia, based on what I've seen in both places and what I've been reading since hitting the road. This much is clear to me: there's no need to lean on race as an explanation.
If some day, science finds that Europeans are genetically so different from Australian Aboriginals as to indicate that we do not come from the same stock - that we are effectively different species - then the government of Australia will have a very difficult ethical issue on its hands. How can you apply Man's law and confer human rights on a race other than the human one? But it would make some things simpler for the likes of you and me. It would give rational expression to that part of us that looks at the state of the Aboriginals today and asks "what the hell is wrong with them anyway?".
Luckily for moral philosophers and Aussie lawmakers, there is no such challenge to face. The rest of us have to get our heads around a more complex, but ultimately more satisfying, answer to silence that persistent suspicion that they are not like us.